To me, the practical meaning of sanctification is clear from scripture, and it is an act (of consecration in resonse to a desire for a life of obedience and holiness) of faith followed by a process of outworking and progressive holiness. I have included some of what I consider the sequence of the 'clarifying' scriptures at the end of this post. **
Romans 8: 13 tells us how to go about the process and also the consequences if we don't:
13 for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live.
For many years I have studied the lives of many of the great saints of the entire church age, and I have seen a pattern that has helped me understand what is occurring in my own personal journey and the journeys of others. This is not an exact pattern, because God works in each of our lives individually, but it or something similar is the common experience of many who desire to consecrate themselves to follow Christ.
-Conviction of sin and recognition of the need of a Savior, followed by a desire to know Christ
-Salvation by faith, often accompanied by an experience of God
-A time of grace and even elation--can be short or long--followed by a period of
-Struggling with sin(s), inward and/or outward, with failure and disillusionment (this is disillusionment of 'self', actually--not of God--and it is ultimately a good thing).
-Recognition of inability to overcome sin in own strength--even to the point of despair
-Many experience during this period absolute no sense of God's presence--some even doubt their salvation--but God, Himself, is not doubted (this is an annihilation of the self, in real, actual experience)
-At this point, a repentant, fervent seeking of God usually occurs--a time of pleading for a deeper work of Grace that can last days, months, even years--which is then followed by a Baptism of the Holy Spirit, or a second work of grace that results in the power within to actively put to death the deeds of the flesh, one at a time, day by day, moment by moment, ever accompanied by an awareness of the fact that it is the power is of God and not of ourselves. This process goes on throughout earthly life and is more and more effortless on our part, as we each day die more to the 'self' and are more alive to Christ--His will becomes our will; His desires become our desires. It is our choice, but it is His power in operation--and it is by His Grace that we even have the grace to make the choice. It is, in essence, ALL Jesus, but it does not violate our free will because it is the desire of our hearts. This is what many saints refer to as the 'exchanged life' i.e., Christ's life in us exchanged in actual experience for our old self life.
John the Baptist distilled this process when he said, "He must increase, but I must decrease." What happened outwardly in that day happens inwardly in each heart that seeks sanctification. We make a decision to give our hearts and bodies to be ruled undividedly by Jesus Christ, then allow Him to possess and rule them in increasing increments as we work out the sanctification that He has worked in. We are initially sanctified positionally before God by faith, and that is worked out day by day in actuality.
Sanctification is not an option. It is the normal Christian life. We are commanded to be perfect, even as our Heavenly Father is perfect (which I take to mean perfect in Love--God's Love), and we are told not to sin. Because God knows we are weak, He provides for our failures and tells us what to do if we do sin, but the standard is that we do not sin. We are to walk in the Light and not sin, but if we do sin, we have an advocate, the Lord Jesus Christ (1 John 2:1).
It is the responsibility of every Christian to read the Bible and understand what God expects of us, and to obey God-- and it is the responsibility of every minister to teach the congregation what God expects and how to progress in sanctification. The church is in mortal danger because of lack of sound doctrine and teaching regarding this subject.
And it is only by the endless mercy and patience of God that I am personally able to claim and use my forum signature. His Grace is perfected in our weakness--if we submit to Him and obey Him (and He gives the Grace to do that, if we will seek it in response to His Love that first sought us!).
Bondservant by Grace
**Here are (some of) the scriptures that make this subject very clear to me.
Rom 8:10-14
10 If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness.
11 But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who dwells in you.
12 So then, brethren, we are under obligation, not to the flesh, to live according to the flesh --
13 for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live.
14 For all who are being led by the Spirit of God, these are sons of God.
Gal 5:19-26
19 Now the deeds of the flesh are evident, which are: immorality, impurity, sensuality,
20 idolatry, sorcery, enmities, strife, jealousy, outbursts of anger, disputes, dissensions, factions,
21 envying, drunkenness, carousing, and things like these, of which I forewarn you, just as I have forewarned you, that those who practice such things will not inherit the kingdom of God.
22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness,
23 gentleness, self-control; against such things there is no law.
24 Now those who belong to Christ Jesus have crucified the flesh with its passions and desires.
25 If we live by the Spirit, let us also walk by the Spirit.
Or maybe I'm just confused and have it all wrong? It's certainly possible. 
